/* -*- Mode: C; c-basic-offset:4 ; -*- */
/*
 *  (C) 2001 by Argonne National Laboratory.
 *      See COPYRIGHT in top-level directory.
 */
#include "mpi.h"
#include <stdio.h>
#include "mpitest.h"

#define MAX_PROCESSES 10

int main( int argc, char **argv )
{
    int              rank, size, i,j;
    int              table[MAX_PROCESSES][MAX_PROCESSES];
    int              row[MAX_PROCESSES];
    int              errors=0;
    int              participants;
    MPI_Comm         comm;

    MTest_Init( &argc, &argv );
    MPI_Comm_rank( MPI_COMM_WORLD, &rank );
    MPI_Comm_size( MPI_COMM_WORLD, &size );

    comm = MPI_COMM_WORLD;

    /* A maximum of MAX_PROCESSES processes can participate */
    if ( size > MAX_PROCESSES ) {
	participants = MAX_PROCESSES;
	MPI_Comm_split( MPI_COMM_WORLD, rank < MAX_PROCESSES, rank, &comm );
    }
    else  {
	participants = size;
	MPI_Comm_dup( MPI_COMM_WORLD, &comm );
    }
    if ( (rank < participants) ) {
	int send_count = MAX_PROCESSES;
	int recv_count = MAX_PROCESSES;

	/* If I'm the root (process 0), then fill out the big table */
	if (rank == 0) 
	    for ( i=0; i<participants; i++) 
		for ( j=0; j<MAX_PROCESSES; j++ ) 
		    table[i][j] = i+j;
	
	/* Scatter the big table to everybody's little table */
	MPI_Scatter(&table[0][0], send_count, MPI_INT, 
		    &row[0]     , recv_count, MPI_INT, 0, comm );
	
	/* Now see if our row looks right */
	for (i=0; i<MAX_PROCESSES; i++) 
	    if ( row[i] != i+rank ) errors++;
    } 
    
    MPI_Comm_free( &comm );

    MTest_Finalize( errors );
    MPI_Finalize();
    return errors;
}
